Shaped crystal growth of langasite-type piezoelectric single crystals and their physical properties

Abstract

We have grown the shape-controlled langasite-type crystals by the μ-PD method. Columnar-shaped La 3 Ta 0.5 Ga 5.5 O 14 (LTG), Ca 3 NbGa 3 Si 2 O 14 (CNGS), Ca 3 TaGa 3 Si 2 O 14 (CTGS), Sr 3 NbGa 3 Si 2 O 14 (SNGS) and Sr 3 TaGa 3 Si 2 O 14 (STGS) crystals were grown using the Pt-Rh crucible with a columnar die in 3 mm diameter at the bottom. All grown crystals indicated high transparency and approximately 3 mm diameter. Their chemical phases was identified as a single phase of langasite-type structure and their lattice parameters were almost same as those of crystals grown by Cz method. In the X-ray rocking curve measurements, the grown crystals indicated equivalent crystallinity to the crystal grown by Cz method. In addition, the piezoelectric constant d 12 of CNGS crystal was 3.98 pC/N and this value was well correlated with those of previous reports.